Pneumatic tool.



FFME# i CHESTER B. ALBREE, OF ALLEGHENY, PFNNSYLVANIA, ASSIGNOR TO THE CHESTER .BJ ALBREE IRON WORKS COMPANY, OF ALLEGHENY,`PENNSYLVANIA,-A CORPORATION OF PENNSYLVANIA.

PNEUMATIG T001..

\ Patented 'april 1e, lees.A

I Application mea December 2o, 190e.v sem Np.' 348,772.

To all tvhom it may concern: Be it known that I, CHESTER B. ALBREE,

i of Allegheny, Allegheny county, Pennsylvania, have invented a new and useful Pneu? matic Tool, of which the following is a'full, clear, and exact description, reference being had to the accompanymg drawings, forming part of this specification, 1n which- Figure 1 is a longitudinal section showing my invention as applied to a pneumatic riveter; Fig. 2 is a similar view showing the parts in another position; Fig. 3 is acrosssection on the line III-III of Fig'. 1 Fig. 4- is a detail view showing another form of the leakage' channel; and Fig. 5 is a view similar` to Fig. 1 showing the invention applied to another type of pneumatic tool.

My invention relates to the class of pneumatic tools ofthe reciprocatory type, and is designed to provide a simple and effective construction whereby reciprocation of the tool does not begin until it is pressed against the work. `Heretoforethe attachments for obtaining this result have been complicated and expensive, whereas my improvement isV of little or no cost, and can be readily applied to tools and motors of different types'. The use of my improvement prevents breaking ofthe piston, cylinder, andV other parts, and

injury byl forcible projection of the working.

tool into space.

In the drawings, referring to the f ormv of Figs. 1 to 4 inclusive, in which I show the invention as applied `to a pneumatic riveter havingan inertia valve, 2 represents the cyl,- inder or barrel having a bore of two different diameters receiving the piston having ortions 3 and 4 of dierent diameters. he front end of the piston acts u on the reciprocating riveting tool or 4tool o othercharad ter 5. v6 is theinlet port which inthe form' shown, leads through. the handle, and is controlled by spring-pressed valve 7 operated by the hand lever 8. The inlet passage 9` is closed by theenlarged portion 3 of the piston when at the extreme forward end of its travel; the bore for this enlarged portion extending somewhat beyondthe inlet opening', as shown at 10. The exhaust er '12 around the por-y tion 4 of the piston, this chamber communi eating by ports 14 with a hole or chamber 15 containing a 4hollow inertia valve 16. Passages 17 lead through the enlarged portion 3 of the piston yto allow entrance of Huid to the port or ports 11j lead sage 18 is formed along the outer surface of"4 the portion 4 of the piston. j In using the tool, when the in letgvalve 7j is 'l opened fluid will enter the inlet channel 9 but l cannot actuatethe piston, owing-to .thecovering of the inlet port by the piston. When, however, the tool 5 is Ypressed against the work its rear end moves t in thecylinder and partiall uncovers the inlet port after havingclose theexhaust passage 18. The piston will then reciprocate in4 the ordinary manner to actuate the tool, the inertia valve performing the same functions v as in former constructions.

The exhaust passage 18 prevents the pres-.

- sure below the piston due to air from port 6 .entering the portion 10 of the bore, from starting the tool into motion. This channel is of such a length that when the tool forces the piston back a sufficient distanee it is cut olf from exhausting to the atmospherel Thissupplemental exhaust port or channel may be formed by simply grooving or recess ing one side of the reduced ortion of the'pis-v ton in any' desired form, or by forming a port or passage in the cylinder Wall', or by a combination lofboth. In any case, if the fluid under pressure leaks past the piston portion 3, or is normally ermitted below the portion 3, it will enter this exhaust channel and pass freely to the atmosphere and not press against the piston and set-it into motion. In Fig. 3 the port is formed by a flattened face 18', while in Fig. 4 I show an angular groove or recess 19.A f The improvement may be easilyfap lied to pneumatic tools havin motors of iHerent types. .Thus in Fi 5 show the invention applied to the valve ess type'of motor wherein the piston has differential diameters. In this form, parts similar to those' in Figs. 1 and 2, are designated by similar numerals with the letter a applied thereto. In this case the Huid in the rear of the piston asses directly into the piston'cavity 20 and t ence through the being used.

'In the form of Figs. 1 to 4, if the tool isv brought into a vertically extending position such that ravity will cause the jplston vto drop down? then of course-the tool will make one forward st'lkeeven where itis not pressed against the wi'k to force back the pistoni. In thiscase,

e piston rearwardly port'14-f to the/exhaust, no valve ar enough to open thev lnlet port,

. space is obviated.

however, the movement of the piston will stop after one forward stroke, since this stroke will carry it far enough to cover the inlet port, the obstruction consisting of the pressed-back tool being removed in such case.

The advantages of my invention result from the use pf the supplemental exhaust passage contrcilled by the movement of the piston and so located as to be open to the atmosphere only when the piston is at the forward end of its possible stroke. By the use of this supplemental channel no piessure can collect beneath the piston, which must rest stationary until such exhaust passage is closed by forcibly pushing the piston back. This supplemental passage relieves any pres sure beneath the piston, whether formed from air leaking through a closed admission portl or from a full supply through an open admission port. In the latter case, there Would be a Waste of air, but such is preferable to permanently injuring the tool, and such Waste could be immediately stopped by simply allovving the throttle valve to cut oii' the supply of moti-ve fluid. The desirable function of not starting the motor until the tool is pressed against the Work is therefore obtained Without extra parts or attachments and at little or no cost. yThe complexion of the tool is but slightly increased, and its life is greatly increased, while the chance of an accident by projecting the Working tool into To save air the tool can be arranged to cover the admission port when the addition exhaust port is open; but although desirable this is not essential.

The form of the motormay be Widely varied, and the invention may be applied to any pneumatic tool whether used for riveting, chipping, or other Work.

1. A reciprocating percussive engine of the iiuid pressure type, iavingsupply and cxhaust ports' controlling normal action of the piston, and provided with an additional exhaust passage controlled by the position of the piston, and always in communication with'the space in front ol the piston, said passage being open to the atmosphere only when the iston is at the extreme end of its forward strolie and closed by the piston in' the other portions of its stroke; substantially as described,

2. A reciprocating percussive engine of the fluid pressure type, having inlet and exhaust ports controlling the normal action of the piston, theinlet )ort being near the forwawfl end of the cylin er and closed by the piston when at the extreme forward end of its stroke, said engine having a supplemental exhaust port controlled by the piston and -always in communication with the space in liront of the piston, said exhaust port being open to the atmosphere only when the piston 1s at the extreme end of its forward stroke and closing the inlet port 5 substantially asl CHESTER B. ALBnEn Witnesses JOHN MiLLEn, H. M. CORWIN. 

